This invention relates to a foldable portable support stand of a type which is especially suitable for use in portable workbenches, such as workbenches of the type including a workpiece supporting and clamping assembly as part of its basic structure.
The prior art has provided a wide variety of types of collaspsible or foldable support stands adapted to support a tray or other suitableform of table-top-like surface. Many of these structures are suitable for use as serving stands or tables for supporting dishes etc., in restaurants and the like. Typical examples of such structures may be found in U.S. Pat. No. 2,354,941 dated Aug. 1,1944 to Treitel, in U.S. Pat. No. 3,106,295 dated Oct. 8, 1963 to Berlin and in U.S. Pat. No. 2,802,578 dated Aug. 13, 1967 to Barile. A common feature of all of these structures is the provision of pairs of legs in a cross-over relationship pinned together by suitable pin means to permit the leg members to be moved relative to one another from a collapsed or folded position relative to one another to an open supporting position. The prior art also provides various arrangements wherein the support stand is integrally connected to a workbench such as in U.S. Pat. No. 1,688,533 issued Oct. 23, 1928 to Eger. In this arrangement the support legs are interconnected together by spaced apart linkage members which maintain the legs in parallelism in both the open supporting position and the folded position. A more recent development is shown in U.S. Pat. No. 3,615, 087 dated Oct. 26, 1971 to R.P. Hickman. This patent discloses a workbench arrangement including a work supporting and clamping assembly which is interconnected to a base structure by supporting members which are capable of movement between a collapsed position wherein the workbench portion is in close juxtaposition to the base structure and a working position in which the workbench is spaced from and supported above the base structure.
One disadvantage of many of the prior art support stands is that they employ a large number of moving parts e.g. pivot pins, links, etc., which tend to wear with use, thus tending to make the support stand less stable and prone to failure. Manufacturing costs, due to the large number of parts employed, tend to be relatively high. Certain of the prior art support stands are unduly bulky and thus cannot readily be stored or carried from place to place.
My copending U.S. patent application Ser. No. 665,201 filed Mar. 9, 1976 entitled "Workpiece Supporting and Clamping Apparatus" discloses an improved form of workpiece supporting and clamping assembly of a type adapted to be positioned on a support stand, table, bench or the like. This assembly includes a generally rigid base frame having a pair of elongated top members mounted on the base frame and lying in a common plane in side-by-side relationship. The top members include longitudinally extending side portions defining surfaces for the clamping of workpieces therebetween. The top members are movable along the base frame toward and away from one another. Suitable clamping means are operatively connected between one of the top members and the base frame to move such top member back and forth to an infinite number of positions along the base frame. Locator means are associated with the other top member thereby to allow it to be manually indexed to and located at any one of a plurality of predetermined positions along the base frame thereby allowing such top member to be quickly positioned relative to the first top member approximately in accordance with the dimensions of the workpiece to be clamped between the top members. The clamping means is operative to move the first mentioned top member relative to the other top member to provide the required clamping forces.